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为优化离子推力器中栅极系统设计,采用三维粒子云网格(PIC)仿真方法对三栅极系统等离子体输运过程进行了仿真,并与两栅极仿真结果进行对比,分析了三栅极特有的减速栅对栅极系统内束流分布、电子返流阀值、截止电流和交叉电流阀值、离子通过率和发散角损失等参数的影响。研究结果表明减速栅的主要作用包括:对离子通过率无影响,对截止电流影响不明显,但可大幅减弱甚至消除交叉电流限制问题;对加速栅腐蚀有明显的抑制作用,工作区间内的加速栅电流降低50%;增强了下游区域的径向电场,部分离子会偏离主束流区域,导致发散角损失增大;可改善加速栅孔附近电势分布,对电子返流阀值影响明显,对于1~4 A的束电流,仅需-60~-50 V的负偏压便可实现对电子返流的抑制。
In order to optimize the gate system design in ion thruster, the plasma transport process in tri-gate system was simulated by three-dimensional particle cloud grid (PIC) simulation method and compared with the simulation results of two grids. The effect of a very slow deceleration grid on beam distribution, electron backflow threshold, cut-off current and cross-current threshold, ion pass rate and divergence angle in the grid system. The research results show that the main functions of deceleration grid include: no influence on ion passage rate, no significant effect on the cut-off current, but significantly reduced or even eliminated the problem of cross-current limit; obvious inhibition on acceleration grid corrosion, acceleration in working area The gate current is reduced by 50%; the radial electric field in the downstream area is enhanced, part of the ions will deviate from the main beam area, resulting in an increase of the divergence angle loss; the potential distribution near the acceleration gate hole can be improved, 1 ~ 4 A beam current, only -60 ~ -50 V negative bias voltage can be achieved on the electronic regurgitation.